Recently, some techniques for dialysis apparatuses serving as blood-purification apparatuses have been proposed, such as a technique of performing priming, blood returning, or substitution (emergency fluid infusion) by using dialysate to be supplied to a dialyzer when dialysis treatment (particularly, on-line HDF or on-line HF) is given, and a technique of using the dialysate as substitution fluid for the treatment of on-line HDF or on-line HF. For example, a dialysis apparatus is disclosed by PTL 1 that includes a dialysate-supplying line having one end connected to a dialysate-extracting port (hereinafter referred to as “collecting port”) provided at a predetermined position of a dialysate-introducing line and the other end connected to a blood circuit (an arterial blood circuit or a venous blood circuit), and a substitution pump provided for supplying the dialysate. With such a dialysis apparatus, when priming, blood returning, or substitution (emergency fluid infusion) is performed, the dialysate in the dialysate-introducing line can be supplied to the blood circuit (the arterial blood circuit or the venous blood circuit) by activating the substitution pump.
Typically, as illustrated in FIG. 15, the collecting port is provided with an opening-and-closing device I that is detachable therefrom and attachable thereto. The opening-and-closing device I is detached from a collecting port 102, and a substitution line or the like is connected thereto. If the substitution line or the like is not connected, the opening-and-closing device I is attached to the collecting port 102 so that the dialysate flowing in the dialysate-introducing line does not leak to the outside. The opening-and-closing device I is provided with a seal member 103 and a cap member 104 that are fixed therein. With the opening-and-closing device I attached to the collecting port 102, a seal portion 103a of the seal member 103 is in contact with the collecting port 102 and can seal the collecting port 102.
The collecting port 102 is provided thereinside with an introducing member 101 into which the dialysate is introduced. With the opening-and-closing device I attached, when fluid such as a cleaning solution or a disinfecting solution is introduced from the dialysate-introducing line through the introducing member 101, the fluid collides with the opening-and-closing device I and flows backward (downward in FIG. 15). Then, the fluid is allowed to flow through the gap between the outer peripheral surface of the introducing member 101 and the inner peripheral surface of the collecting port 102 into the dialysate-introducing line. In such a process, it is preferable to allow the cleaning solution and the disinfecting solution to reach a top end 102a of the collecting port 102 so that the top end 102a is cleaned and disinfected. Therefore, the seal portion 103a of the seal member 103 is configured to come into contact with the outer peripheral wall of the collecting port 102 and seal the collecting port 102.